WO2006111823A1

WO2006111823A1 - Heating Insole or Shoe

Info

Publication number: WO2006111823A1
Application number: PCT/IB2006/000916
Authority: WO
Inventors: Giacomo Manenti; Davide Pavanello; Davide Manenti
Original assignee: Suntech S.R.L.; Insalp S.R.L.
Priority date: 2005-04-18
Filing date: 2006-04-14
Publication date: 2006-10-26
Also published as: ITMI20050678A1

Abstract

Heating insole or shoe comprising: a resistive element made with PTC ink printed on a flexible material (2) capable of producing heat if supplied with electric current, preferably low voltage; a lithium polymer battery (3) (or similar) capable of supplying said resistive element.

Description

Heating insole or shoe

FIELD OF THE INVENTION

The present invention refers to a heating insole or shoe, mainly to an insole or a shoe capable of producing heat underneath the foot. PRIOR ART

Heating the body's extremities, especially the feet, can be a problem in low temperatures, especially if it is necessary to remain in the open for a long time, for instance when you are carrying out sport activities or are working. The problem is made more difficult by the fact that the shoe is always in contact with the cold floor, and sometimes it can be wet or covered in snow, and the foot may be sweaty. Several solutions have been put forward, including heating the shoe with electricity; but the proposed solutions have been unsatisfactory in terms of comfort of the shoe, the presence of resistors can constitute an uncomfortable element in certain points of the shoe, mainly under the sole of the foot, with regards to the possibility of supplying, in a comfortable and adequate way, the heating system, which is also the cause of autonomy problems that limit the use of shoes made for outside and lengthy usage.

Furthermore the possibility to regulate easily and quickly the amount of heat generated is a critical problem, as even small changes from an optimum condition can be the cause of some discomfort. It would be advisable for the system to be self-regulating so as to reduce to a minimum the need of intervention whilst using the shoe and it would also self-regulate energy consumption.

SUMMARY

The above mentioned problems have now been solved according to the first embodiment of the invention, through a heating insole or shoe comprising:

A resistive element, made with an ink which has PTC characteristics, capable of producing heat if fed with an electric current; a battery capable of supplying the above mentioned resistive element.

Preferably, the resistive element can be fed with a continuous low tension. According to a preferred embodiment said element should be incorporated in the insole or in the bottom of the shoe in the sole or above it or in a fixed insole.

According to another embodiment, the resistive element is printed on a sheet of material, preferably flexible, for example a plastic material of the type commonly used for said applications. Said resistive element is made with ink which has PTC (positive temperature coefficient) characteristics, as defined in the Patent Application WO 03105530. Preferably it should be a polymer lithium battery (available in commerce under the name Ultralifebatteries, Sinter , Hyper, Hicharge). LIST OF FIGURES

The present invention will now be illustrated through a detailed description of preferred embodiments, but not exclusive, given only as an example, with the aid of the figures enclosed, in which:

Figure 1 represents the scheme of an insole according to the present invention, including the elements and the circuits, in part necessary and in part optional, for their functioning; Figure 1a represents schematically a battery charger for the insole. Figure 2 represents schematically a shoe adapted so that it can house an insole according to a particular embodiment of the invention.

Figures 3 and 3a represent schematically the traced path of couples of printed electrodes, which are part of a circuit capable of carrying current to the resistive element (not shown), according to particular embodiments of the invention. DETAILED DESCRIPTION OF AN EMBODIMENT.

With reference to figure 1 , a way of making an insole 1 is described according to an embodiment of the invention; it can be made in a suitable material, such as a cellulose material, leather, expanded material or any other material commonly used; a preferred material is polyurethane due to its hygienic qualities and also for its specific characteristics of thermal and electrical insulation.

The insole, comprises the resistive element 2 capable of generating heat; the following description can also be valid for the sole of a shoe, by changing the necessary elements. The resistive element can be buried in a suitable material; according to a preferred embodiment of the invention it is a resistive circuit printed on a plastic material, for example those sold as Kapton or Mylar, or any other suitable material. It can be made in the known way with ink with PTC characteristics, as defined in WO03105530, and sold by Coates Electrographics (division of Sun Chemical Inc.) because they are remarkably endowed with self- regulating features and permit the setting of circuits capable of reaching and maintaining a temperature within precise limits without the need of further interventions, with energy saving advantages. This is very important in the case of a shoe, as seen above. Element 2 can suitably extend itself in the insole or shoe, preferably located only in the front part, in particular under the sole of the foot. In this way it can generate sufficient heat starting from the zone where the need is greater for anatomical physiological reasons. The circuit can be made with known procedures, such as screen printing, ink jet printing, transfer... The insole thus produced can be made breathable by piercing, also where the resistive element is located, especially if it is a heating circuit as described above. The insole comprises a battery 3, preferably located in the heel part, because the resistive element is in the front part and because in these zones more thickness and rigidity are generally required or anyway tolerated. The battery should have adequate capacity characteristics; the polymer lithium batteries are preferred. They have been found to unite the requirements of compactness (it is possible to make them with a thickness of 3 mm and less) resistance, ductility, capacity and absence of memory effect, which is an important embodiment of the invention when the battery cannot be substituted in the insole. The insole contains a series of circuits to connect the battery and the resistive element one another or with other control elements internal or external to the insole. The circuits can be conductors, such as wires buried in the insole, can be printed circuits on flexible sheets even, if it is considered better, on a same sheet where the resistive circuit 2 is printed. The insole can have a pressure switch 4, of the know type, capable of allowing the feeding of element 2 only if the foot of the user is there, the thermal switch 5, for example a bulb switch, favours a better regulation of the heat, intervening at determined set temperatures, excluding the production of heat if the temperature of the foot, preferably at an adequate distance from the resistive element, exceeds a certain value.

It is necessary to provide other control elements that must be accessible from the outside. They can be placed on the surface of the insole, as well as on the side surface 6. Connection means to other external elements are provided, for example a battery charger. For example, a first connector 7, that could connect the connecting stripe 8 which can have more conductors printed on a flexible plastic strip made with known techniques, that can protrude from the opening of the shoe even if the foot is in the shoe without any discomfort is provided. The conductors connect in a suitable way the insole circuit to other elements such as a manual switch 9 that the user can use to switch on or off the foot heater, a LED (light emitting diode) 10 that indicates that the insole is turned on and which can also change colour to indicate the battery charge state. Instead of or together with the manual switch a remote control switch can be provided, connected to strip 8 or positioned in another advisable way, preferably placed inside the insole 1. According to a possible embodiment of the invention, it is possible to use remote controlled switches, for example by a magnet or a remote control device. In the first case it can be, for example, a reed contact, preferably bistable, driven alternatively, by switching it on or off through opposite poles of a magnet. In the second case, it can be remote control capable of sending a turning on signal, repeating it at predetermined periods, and a turning off signal repeating it in the same way, for an adequate period of time. Bidirectional systems can also be provided with an acknowledgement from the insole circuit to indicate it has received and/or interrupted the signal input. In fact, as it is not a directly controlled switch, with the possibility of failing to receive the command, and the user not having an immediate sensation if it is switched on or off, it is better to assure oneself of the correct functioning in this or in another way. This mainly if any connection with the external part of the shoe is eliminated, by eliminating for example the second contact 11 and stripe 8, which is made possible if remote control switches without physical contact are used.

It is possible, and is advisable especially if contacts and external elements to the shoe have been eliminated, for the LED, as described above, to be directly in the insole, for example buried, but visible on its surface; preferably, the LED can be positioned on the upper face where the heel is, so that it can be visible at least from the outside when the shoe is not worn. The second connector 11 , when present, allows the connection to a battery charger, for example connectable to the electric network, suitable for a battery 3 (fig. 1a) of the quick charging or slow charging type. A two way charger can be advantageous, in order to connect simultaneously the pair of insoles or the pair of shoes. It can advantageously have separated two way charge indicators. It is preferably for the connection between chargers and the second connector, if present, to be detachable. Also other types of connectors, in addition or in substitution of the ones already described, can be provided, for example the number 12 positioned on the surface of the insole and from here accessible. If strip 8 or a connection mean to the outside is missing, it is necessary for the charging connector, unless an induction charge is provided, to be positioned on the insole, in a suitable position, for example in the zone where connector 7 is shown in figure 1. In this case, the connector could be provided only for the battery charger. The connector can be a jack pin or of another common type. To indicate the functioning of the insole or shoe, devices capable of generating a vibration perceivable by the user, for example devices with an eccentric rotating mass can be provided. They can work briefly at set time intervals, to indicate that the heating system is operative. Other optional elements can be the inductor 13, placed in a suitable way, preferably towards the edge of the insole to charge the battery with a magnetic induction charger, outside the shoe or the insole, which could be on a suitable mat or small piece of furniture. It can be substituting the means to connect a battery charger or it can be an additional one. Also an automatic switch or a resistive variator 14 for preferential heat regulation purposes, accessible for example from one side or from a surface of the insole is provided.

Other elements can be added according to the requirements, for example a charging system with piezoelectric elements activated when the user walks; or small solar panels can be connected, obviously outside the shoe. One can also have safety elements and heat limitation devices such as cut-off put in series with the heating elements, and/or other PTC limiting devices to limit the temperature in case of failure, such as PTC resistors for printed circuits. The insole can be made in the usual ways, for example by injection moulding, in a mould containing the above mentioned elements, or made up of layers in between which the circuits can be placed. It can be made in different materials, such as those usually used; it can also be made with a gel containing envelope or any other suitable material, wherein the elements described above are inserted. Other ways of making the insole can be designed, using the known techniques. It is possible for the sole to have a top interchangeable cover, for example a cloth or other self-adhesive material that could include the resistive element 2, if one wants it to become interchangeable, without the need to change the whole sole; the interchangeable cover also guarantees hygiene without the need to change the whole sole. In the case of a shoe with an integrated heating element, a standard interchangeable insole can be provided.

The circuits can be printed on the first layer of the insole, of a suitable material, for example fiberglass, or plastic material, and the insole can be then completed by injection or expansion moulding.

According to an embodiment of the invention, it is possible for the insole to include a cloth or leather layer or a layer of cork on a face of which a circuit is applied, comprising the PTC resistors. Techniques to create such circuits are known, for example similar techniques are described in the International Application WO03105530. The rest of the insole in that case can also be made by moulding or with other techniques, for example expansion cold moulding of a polyurethane material. Moreover, the battery and the other circuit elements can be applied to the above mentioned layer or material, for example, by adhesives. In this embodiment, or in other embodiments, one must always bear in mind particular incompatibilities between materials. For example common cross-linking agents used for polyurethane during moulding, can damage the PTC inks, that must be protected, for example with a protective film (for example thermoplastic polyurethane) on top of the circuit, where the resistive elements are present, before moulding the insole. Seats for removable batteries can also be provided. For example, an outline of a shoe is shown in figure 2 with an insole according to the present invention. The insole has the two additional contacts 15 on the bottom surface (opposite the foot). In the heel of the shoe there is a space 16 for the spare battery, which is connected to contacts 15 through connections, for example a spring 17 through holes that connect the inside of the shoe to the space 16. The contacts can be in part buried in the shoe material, to assure a good seal. In this way, the additional battery can be simply inserted inside the space for it to be in contact with the insole circuits, this allows an easy replacement also whilst in use, apart from a spare charge for a greater autonomy. This battery can work together or substitute the insole battery; this means that a shoe can be made according to the invention which includes an insole with heating elements and circuits, but without a battery which is inside the shoe. Also in the case of an insole, removable batteries can be provided as well as replaceable ones instead of the fixed type. For example, it is possible to provide a seat with suitable contacts, wherein the battery can be inserted or taken out through an opening placed, for example, on the back end of the heel. This seat can be, for example, an open envelope with a suitable opening, capable of housing a battery, having internal contacts connected in a suitable way to the circuit of the insole, and buried in it during moulding.

In the case of removable insoles, for example skiing boots, they can have a small tongue at the back to make them easily removable from the boot. Generally speaking, the resistive elements can be created as a printed resistive circuit, comprising at least two flat electrodes applied to a support, as seen, of a suitable material, connected one to the other by a plurality of traces marked with PTC ink; the portions of traces included between the two points in contact with the electrodes will act as heating resistances. The electrodes will be of a suitable material, and they can also have the shape of printed or applied tracks to the support by various known techniques; these tracks are connected, for example soldered or glued with the rest of the circuit of the insole. The shapes of the electrodes can be of the known type. It has been noted that, for very thin electrodes, as commonly used, if the resistive element is buried in the insole material or stuck to part of the insole, it may occur that due to continuous bending during walking, a breakage of the electrodes is determined in the maximum bending point, contrary to what happens to similar resistive elements when taken alone, that adequately resist to such bending cycles simulating walking. The breakage happens in the zone of maximum bending of the insole, on the sole of the foot and toes, exactly where the resistive element is preferably placed. The breakage of the electrodes depending on the point of breakage and on the shape of the electrodes, can determine the non functioning of all or part of the resistive element.

According to a possible embodiment of the invention, the resistive element is a resistive circuit comprising two electrodes connected one to the other by a plurality of trace portions made in PTC ink; it may be a printed circuit, for example on a sheet of flexible material in one of the ways seen above. At least one of the electrodes, or both, are connected to the insole circuit, that can preferably be made with normal electric wires placed in the front (towards the point of the shoe), with regards to the point of maximum bending induced by walking when the insole or shoe are worn; preferably the connection is in a region in the third central part of the width of the insole in the connecting point. Different forms of electrodes can be conceived to minimise the effects of a possible breakage. For example, in figure 3a the electrodes 31 and 32 are shown. These are placed in parallel and shaped as a spiral. A series of traces (not shown) made with PTC ink, for example a series of parallel strips or shaped as radially or as a grid, is superimposed to said electrodes so as to connect them, giving a plurality of resistors as mentioned above. If the electrodes are connected to the battery for points 33 and 34 in the middle of the spiral, placed in front of the insole's zone of maximum bending, a failure in said zone, for example in one or more points of line A, obviously will still allow for the central part of the circuit to carry on working. Another example is given in figure 3b, showing electrodes 35 e 36. As one can see electrode 36 completely surrounds electrode 35; both have a comb shape and electrode 35 shows a central enlarged part 37 that can be placed lengthwise in the insole. The PTC ink traces, which are not shown, can be lines parallel with such central part 37. The two electrodes present a higher resistance to breakage for example along the line B, due to the dimensions of the longwise parts. If the electrode 35 is connected for the central part, before line B, that represents the zone of maximum bending, it can be seen how a breakage can exclude a limited part of the circuit. Also the electrode 36 can be connected fore with respect to said zone, but its shape would anyway require a large breakage in many points to exclude part of the circuit.

According to a possible embodiment of the invention the heating element 2 is made as a thermo-resistor, wherein which the two electrodes are separated by an insulating material which has a plurality of holes, and wherein a layer or a plurality of traces made with PTC ink in one of the faces of the layer of insulating material connect the two electrodes through said holes. According to a preferred embodiment at least the PTC ink traces and the electrode implemented in the same part of the insulating layer have a reticulated, staggered pattern so that the electrode is not present in correspondence of the holes of the insulating layer, whilst the PTC ink traces are, preferably in the crossing points of the ink lines with different directions. The electrode on the opposite part of the insulating layer obviously is present in correspondence with the holes where it is in contact with the PTC ink traces. Similar thermo-resistors and their method of production are described in the International Application WO 03/105530. This type of thermo- resistor has the advantage that the breakage of an electrode in one or more points (depending on the geometry and dimension of the weave) does not interrupt its continuity, allowing the whole of the thermo-resistor to work. Preferably the electrodes of the thermo-resistor are connected, as seen above, in one or more points to the circuit of the sole in front of the zone of maximum bending, preferably in the third central widthwise part.

Claims

1. A heating insole or shoe comprising: a resistive element (2), made with an ink which has PTC characteristics, capable of producing heat if fed with an electric current; a battery (3) capable of feeding said resistive element.

2. The insole or shoe according to claim 1 , wherein said battery is a lithium polymer battery.

3. The insole or shoe according to any of the preceding claims, wherein said resistive element is printed on a sheet of flexible material and is placed in correspondence of the sole of the foot.

4. The insole or shoe according to any of the preceding claims, wherein said battery is positioned in correspondence of the heel.

5. The insole or shoe according to any of the preceding claims comprising an externally controlled switch, by a remote control or a magnet.

6. The insole o shoe according to any of the preceding claims comprising a vibrating device capable of indicating the functioning of the insole.

7. The insole or shoe according to any claim from 1 to 4 comprising connection means (7, 8, 11) with external control elements.

8. The insole according to claim 7, wherein said means include a first connector (7) placed on a lateral surface of the insole and accessible through it.

9. The insole according to claim 7 or 8, wherein said means include a flexible stripe (8) having conductors and a second external connector (11).

10. The insole according to any claim from 7 to 9, wherein said means allow a removable connection with a battery charger.

11. The insole o shoe according to any of the preceding claims comprising an inductor (13) for charging the battery by magnetic induction.

12. The insole o shoe according to any of the preceding claims comprising a thermal switch (5), or a limiting device comprising a PTC element.

13. The insole o shoe according to any of the preceding claims comprising a pressure switch (4).

14. The insole according to any of the preceding claims wherein said battery and resistive element are buried in the insole body.

15. The insole o shoe according to any claim from 1 to 13 wherein said battery is removable.

16. The insole according to any of the preceding claims made by injection or expansion moulding.

17. The insole according to any of the preceding claims made in polyurethane.

18. The insole according to any of the preceding claims wherein said resistive element is interchangeable and combined with an interchangeable upper lining of the insole.

19. The insole or shoe according to any of the preceding claims wherein said resistive element is a heating circuit comprising two flat electrodes connected to each other by a plurality of trace portions made with PTC ink.

20. The insole o shoe according to claim 19, wherein at least one of said electrodes is connected to the electric current in at least one point fore with respect to the maximum bending zone of the insole or sole of the shoe determined by the action of walking.

21. The insole or shoe according to claim 19 or 20, wherein said electrodes are parallel tracks with a spiral shape.

22. The insole or shoe according to claim 19 or 20, wherein one of said electrodes surrounds the other completely.

23. The insole or shoe according to claim 19 or 20, wherein the heating element is made as a thermo-resistor both electrodes of which are separated by a layer of insulating material with a plurality of holes, and wherein a layer or a plurality of traces made with PTC ink on one of the faces of the insulating material layer connect the two electrodes through said holes.

24. The insole or shoe according to claim 23, wherein the PTC ink traces and the electrode placed on the same side of the insulating layer have a reticulated, staggered pattern so that the electrode is not present in correspondence of the holes of the insulating layer, whilst the PTC ink traces are preferably in the crossing points of the ink lines with different directions.